/* rain.c -- 针对若干年的降水量数据, 计算年降水总量， 年降水平均量,以及月降水平均量 */
#include <stdio.h>

#define MONTHS 12		//一年的月份数
#define YEARS 5 		//降水量数据的年数 

int main(void)
{
	//把数组初始化为2000年到2004年的降水量数据
	const float rain[YEARS][MONTHS] ={
			{4.3,4.3,4.3,3.0,2.0,1.2,0.2,0.2,0.4,2.4,3.5,6.6},
			{8.5,8.2,1.2,1.6,2.4,0.0,5.2,0.9,0.3,0.9,1.4,7.3},
			{9.1,8.5,6.7,4.3,2.1,0.8,0.2,0.2,1.1,2.3,6.1,8.4}, 
			{7.2,9.9,8.4,3.3,1.2,0.8,0.4,0.0,0.6,1.7,4.3,6.2},
			{7.6,5.6,3.8,2.8,3.8,0.2,0.0,0.0,0.0,1.3,2.6,5.2}
	};
	const float (* ptr_rain)[MONTHS] = rain;                                                    
	float subtot, total;
	int year,month;
	
	printf(" YEAR RAINFALL (inches)\n");
	for (year = 0, total = 0; year < YEARS; year++)
	{ // for each year, sum rainfall for each month
		for (month = 0, subtot = 0; month < MONTHS; month++)
				subtot += *( *(ptr_rain + year) + month);
		printf("%5d %15.1f\n", 2000 + year, subtot);
		total += subtot; // total for all years
	}
	printf("\nThe yearly average is %.1f inches.\n\n",
			total/YEARS);
	printf("MONTHLY AVERAGES:\n\n");
	printf(" Jan Feb Mar Apr May Jun Jul Aug Sep Oct");
	printf(" Nov Dec\n");
	for (month = 0; month < MONTHS; month++)
	{ // for each month, sum rainfall over years
		for (year = 0, subtot =0; year < YEARS; year++)
			subtot += *( *(ptr_rain + year) + month);
		printf("%4.1f", subtot/YEARS);
	}
	printf("\n");
	
	return 0;
}